CN112055632B

CN112055632B - Coated cutting tool and method for manufacturing same

Info

Publication number: CN112055632B
Application number: CN201980029433.0A
Authority: CN
Inventors: 府玻亮太郎
Original assignee: Moldino Tool Engineering Ltd
Current assignee: Moldino Tool Engineering Ltd
Priority date: 2018-05-30
Filing date: 2019-03-27
Publication date: 2023-06-30
Anticipated expiration: 2039-03-27
Also published as: US20210162510A1; JP6927431B2; CN112055632A; KR102421533B1; WO2019230166A1; EP3804891A1; EP3804891A4; US11511352B2; JPWO2019230166A1; KR20200136991A

Abstract

A coated cutting tool (40) has a substrate-side single layer portion (33) and a laminated portion (34) in this order from the substrate (31) side as a hard coating. The base material side single layer part (33) is composed of a hard coating of a nitride main body, wherein the hard coating of the nitride main body contains at most Al in terms of the proportion of metal (semi-metal-containing) elements, and the total content ratio (atomic ratio) of Al and Cr is 0.9 or more and at least B. The laminated part (34) is formed by alternately laminating an a layer of a nitride main body and a B layer of the nitride main body, wherein the a layer of the nitride main body contains at least B and the maximum Ti is calculated by the proportion of metal (containing semi-metal) elements; the B layer of the nitride body contains at least Cr and B, and contains Al in a proportion of metal (semi-metal-containing) elements in the largest amount. The lamination period of the layer a and the layer b in the film thickness direction is 5-100 nm. The X-ray diffraction pattern of the portion constituted by the substrate-side single layer portion (33) and the laminated portion (34) is constituted by a single structure of fcc.

Description

Coated cutting tool and method for manufacturing same

Technical Field

The present invention relates to a coated cutting tool exhibiting excellent wear resistance and a method for manufacturing the same.

The present application claims priority based on patent application 2018-103380 of Japanese application, 5-30, the contents of which are incorporated herein by reference.

Background

Various coated cutting tools used in severe cutting processes (high feed process, high speed process, etc.) have been proposed.

Japanese patent No. 4714186 (patent document 1) discloses a coated cutting tool having a multilayer coating layer in which two or more first film-forming layers each composed of (AlCrB) N or (AlCrB) CN and unavoidable impurities and second film-forming layers each composed of SiN, siCN, CN or CNB and unavoidable impurities are alternately laminated on a base material.

Japanese patent application laid-open No. 2018-50530 (patent document 2) discloses a coating layer comprising a base layer 212 comprising (AlCr) N, a multilayer film 216 comprising a layer a comprising (AlCrB) N and a layer B comprising (AlCr) N laminated in this order on a substrate, and an outermost layer 220 comprising (AlCrB) N (paragraphs [0022], [0024], fig. 2).

Japanese patent No. 5684829 (patent document 3) discloses a multilayer coating system having a multilayer structure in which (AlCrB) N independent layers and (TiAl) N independent layers are alternately laminated on a substrate (paragraph [0014 ]).

Japanese patent application laid-open No. 2004-136430 (patent document 4) discloses a technical idea of laminating a (TiB) N film and a (TiAlN) hard film or a (CrAl) N hard film having excellent oxidation resistance and having a multilayer structure (paragraph [0017 ]).

Patent document 1: japanese patent No. 4714186

Patent document 2: japanese patent application laid-open No. 2018-50530

Patent document 3: japanese patent No. 5684829

Patent document 4: japanese patent application laid-open No. 2004-136430

When the coated cutting tool described in patent documents 1 and 2 is used, for example, when cutting a carbon steel (workpiece), the flank wear is suppressed, but the flank wear is liable to progress, depending on the properties of the AlCrN-based coating film of the cutting tool.

The multilayer coating system described in patent document 3 and the coating tool described in patent document 4 lack the laminated portion (combination of a layer and b layer) according to the present invention, and the flank wear and the rake wear cannot be suppressed in a well-balanced manner.

Disclosure of Invention

Accordingly, an object of the present invention is to provide a novel high-performance coated cutting tool exhibiting more excellent wear resistance than conventional coated cutting tools having an (AlCr) N coating film or a (TiB) N coating film formed thereon, and a method for manufacturing the same.

The coated cutting tool of the present invention has a hard coating film on a substrate, and is characterized in that the hard coating film has a substrate-side single layer portion and a laminated portion in this order from the substrate side, the substrate-side single layer portion is composed of a hard coating film of a nitride body, the hard coating film of the nitride body contains at most Al in terms of a proportion of metal (semi-metal-containing) elements, the total content ratio (atomic ratio) of Al and Cr is 0.9 or more, and contains at least B, the laminated portion is composed of alternating layers of an a layer of the nitride body and a B layer of the nitride body, and the a layer of the nitride body contains at most Ti in terms of a proportion of metal (semi-metal-containing) elements, and contains at least B; the layer B of the nitride body contains at least Cr and B in a maximum amount of Al in terms of the proportion of metal (semi-metal-containing) elements, and the stacking period of the layer a and the layer B in the film thickness direction is 5 to 100nm, and the X-ray diffraction pattern of the portion composed of the substrate side single layer portion and the stacked portion is composed of a single structure of fcc.

In the coated cutting tool, preferably, the thickness (t 1) of the base material side single layer portion is 1.0 to 5 μm, the thickness (t 2) of the entire laminated portion is 0.5 to 2.5 μm, and the thickness ratio (t 1/t 2) of the base material side single layer portion to the entire laminated portion is 1.0 to 5.

In the coated cutting tool, the laminated portion preferably has a surface-side single layer portion, the film thickness (t 3) of the surface-side single layer portion is 0.3 to 5 μm, the X-ray diffraction pattern of the portion constituted by the base-side single layer portion, the laminated portion, and the surface-side single layer portion is constituted by a single structure of fcc, the surface-side single layer portion is constituted by a hard coating of a nitride body, al is the largest in proportion of metal (semi-metal-containing) elements in the hard coating of the nitride body, and the total content ratio (atomic ratio) of Al and Cr is 0.9 or more, and at least B is contained.

In the coated cutting tool, preferably, a ratio I (200)/I (111) of an X-ray diffraction peak I (200) of a (200) plane to an X-ray diffraction peak I (111) of a (111) plane in the X-ray diffraction pattern is 0.2 to 0.37.

In the coated cutting tool, preferably, a ratio I (311)/I (111) of an X-ray diffraction peak I (311) of a (311) plane to an X-ray diffraction peak I (111) of a (111) plane in the X-ray diffraction pattern is 0.03 to 0.15.

The method for producing a coated cutting tool according to the present invention is characterized in that the coated cutting tool is produced by an arc ion plating method, and the target for forming the base material side single layer portion and the b layer is composed of an AlCrB alloy or an AlCrBC alloy having the following general formula: al (Al) _α Cr _1-α-β-γ B _β C _γ (wherein, alpha, 1-alpha-beta-gamma, beta and gamma respectively represent the atomic ratio of Al, cr, B and C, and the numbers of alpha, beta and gamma satisfy the conditions that alpha is more than or equal to 0.4 and less than or equal to 0.8, beta is more than or equal to 0.04 and less than or equal to 0.165, and gamma is more than or equal to 0 and less than or equal to 0.035); the target for forming the a layer is composed of a TiB alloy having the general formula: ti (Ti) _1-δ B _δ (wherein 1-delta and delta each represent an atomic ratio of Ti and B, and delta is 0.1.ltoreq.delta.ltoreq.0.5), the substrate temperature is 400 to 550 ℃ in a nitrogen atmosphere having a total pressure of 2.7 to 3.3Pa, the bias voltage applied to the substrate when forming the substrate-side single layer portion is-160V to-110V, and the bias voltage applied to the substrate when forming the laminated portion is-140V to-80V.

In the method for manufacturing a coated cutting tool, the method preferably includes a step of forming a surface side single layer portion on the laminated portion, and the bias voltage applied to the base material when forming the surface side single layer portion is set to-160V to-100V.

In the method for manufacturing a coated cutting tool, it is preferable to use the same AlCrB alloy or AlCrBC alloy as the base material side single layer portion as the target for forming the surface side single layer portion.

In the method for manufacturing a coated cutting tool, it is preferable that arc current is simultaneously applied to the target for forming the a layer and the target for forming the b layer when the laminated portion is formed.

The coated cutting tool of the present invention comprises a base material having a hard coating film comprising a base material side single layer portion and a laminated portion in this order from the base material side, wherein the base material side single layer portion is composed of a hard coating film of a nitride body in which Al is the largest in terms of the proportion of metal (semi-metal-containing) elements, the total content ratio (atomic ratio) of Al to Cr is 0.9 or more, and at least B is contained, and the laminated portion is composed of an a layer of a nitride body in which Ti is the largest in terms of the proportion of metal (semi-metal-containing) elements and at least B is contained, and a B layer of a nitride body in which Ti is alternately laminated; the layer B of the nitride body contains at least Cr and B in a maximum amount of Al in terms of the proportion of metal (semi-metal-containing) elements, and the stacking period of the layer a and the layer B in the film thickness direction is 5 to 100nm, and the X-ray diffraction pattern of the portion composed of the substrate side single layer portion and the stacked portion is composed of a single structure of fcc. Therefore, the flank wear and the rake wear are well balanced and suppressed as compared to conventional coated cutting tools having an (AlCr) N coating or a (TiB) N coating formed thereon. By this action, the coated cutting tool of the present invention has high performance and long life.

According to the method for manufacturing a coated cutting tool of the present invention, the novel coated cutting tool of the present invention having high performance can be provided.

Drawings

Fig. 1 is a front view showing an example of an arc ion plating apparatus for forming a hard coating film that can be used for the coated cutting tool of the present invention.

Fig. 2 is a schematic diagram illustrating an example of a cross-sectional structure of a coated cutting tool according to the present invention.

Fig. 3 is a Scanning Electron Microscope (SEM) photograph (magnification 20000 times) showing a cross section of the coated cutting tool of example 1.

Fig. 4 is a Scanning Electron Microscope (SEM) photograph (magnification 20000 times) showing a cross section of the coated cutting tool of example 4.

Fig. 5 is a Scanning Electron Microscope (SEM) photograph (magnification 20000 times) showing a cross section of the coated cutting tool of example 6.

Fig. 6 is a graph showing an X-ray diffraction pattern of a portion of the hard coating film in a cross section of the coated cutting tool of example 1 in which the substrate side single layer portion and the laminated portion are coated on the substrate.

Fig. 7 is a graph showing an X-ray diffraction pattern of a portion of a hard coating film in a cross section of the coated cutting tool of example 4 in which a substrate side single layer portion, a laminated portion, and a surface side single layer portion are coated on a substrate.

Fig. 8 is a graph showing an X-ray diffraction pattern of a portion of a hard coating film in a cross section of the coated cutting tool of example 6 in which a substrate side single layer portion, a laminated portion, and a surface side single layer portion are coated on a substrate.

Fig. 9 is a graph showing an X-ray diffraction pattern of a portion of the hard coating film in a cross section of the coated cutting tool of comparative example 1.

Fig. 10 is a dark field image (magnification 1600000) of a Transmission Electron Microscope (TEM) of the laminated portion of example 1.

Fig. 11 is a photograph showing a crystal structure resolved from a nanobeam diffraction pattern of the a layer in position 4 of the lamination part of fig. 10.

Fig. 12 is a photograph showing a crystal structure resolved from a nanobeam diffraction pattern of the b layer in position 5 of the lamination part of fig. 10.

Fig. 13 is a perspective view showing an example of a blade base material constituting a coated cutting tool according to the present invention.

Fig. 14 is a schematic view showing an example of an indexable insert type rotary tool to which an insert is attached.

Detailed Description

The embodiments of the present invention will be described in detail below, but the present invention is not limited thereto, and may be modified or improved as appropriate based on common knowledge of those skilled in the art without departing from the technical spirit of the present invention. In addition, the description relating to one embodiment may also apply directly to other embodiments unless otherwise specified.

[1] Coated cutting tool

The coated cutting tool of the present embodiment has a hard coating film on a substrate, and the substrate-side single layer portion and the laminated portion are formed in this order from the substrate side as the hard coating film, wherein the substrate-side single layer portion is composed of a hard coating film of a nitride main body, and the hard coating film of the nitride main body contains Al in a ratio of metal (semi-metal-containing element) of at most 0.9 or more in total content ratio (atomic ratio) of Al and Cr and at least B. The laminated part is formed by alternately laminating an a layer of a nitride main body and a B layer of the nitride main body, wherein the a layer of the nitride main body contains at least B and the maximum Ti is calculated by the proportion of metal (containing semi-metal) elements; the B layer of the nitride body contains at least Cr and B, and contains Al in a proportion of metal (semi-metal-containing) elements in the largest amount. The lamination period of the layer a and the layer b in the film thickness direction is 5-100 nm. The X-ray diffraction pattern of the portion constituted by the substrate-side single layer portion and the laminated portion is constituted by a single structure of fcc.

Fig. 2 is a schematic diagram showing an example of a cross section of the coated cutting tool 40 according to the embodiment. The coated cutting tool 40 has a base material 31, a modified layer 32 provided on the surface of the base material 31 as required, and a base material side single layer portion 33 and a laminated portion 34 provided in this order on the modified layer 32. The lamination portion 34 is a layer in which a layer and b layer are alternately stacked in the above lamination cycle.

The coated cutting tool 40 has at least a hard coating composed of a base material side single layer portion 33 and a laminated portion 34. The coated cutting tool 40 may have a hard coating composed of the base material side single layer portion 33, the laminated portion 34, and the surface side single layer portion 35. Preferably, the X-ray diffraction pattern of the portion of the hard coating is composed of a single structure of fcc.

(A) Substrate material

The substrate needs to be a material having high heat resistance and suitable for physical vapor deposition. Examples of the material of the base material include ceramics such as cemented carbide, cermet, high-speed steel, tool steel, and cubic boron nitride (cBN). The material of the base material is preferably a cemented carbide base material or a ceramic base material from the viewpoints of strength, hardness, abrasion resistance, toughness, thermal stability, and the like. The cemented carbide is composed of a binder phase of tungsten carbide particles and Co or an alloy mainly composed of Co. The content of the binder phase is preferably 1 to 13.5 mass%, more preferably 3 to 13 mass%, based on the total (100 mass%) of the tungsten carbide and the binder phase. When the content of the binder phase in the cemented carbide is less than 1 mass%, toughness is insufficient, and when it exceeds 13.5 mass%, hardness (wear resistance) is insufficient. The hard coating according to the present embodiment can be formed on any of the green surface, the abrasive surface, and the edge-treated surface of the sintered substrate.

(B) Modified layer of cemented carbide substrate

In the case where the substrate is a cemented carbide, it is preferable to irradiate the surface of the substrate with ions generated from a target of a TiB alloy (hereinafter also referred to as "ion bombardment") to form a modified layer having an fcc structure with an average thickness of 1 to 10 nm. The main component of the cemented carbide, tungsten carbide, has an hcp structure, and the modified layer is composed of the same fcc structure as the substrate-side single layer portion. The base material of the cemented carbide and the modified layer are preferably continuous in portions of 30% or more, more preferably 50% or more, and particularly preferably 70% or more of the crystal grains at their boundaries (interfaces). With this structure, the base material of the cemented carbide and the base material side single layer portion are firmly bonded together by the modified layer.

In the coated cutting tool having the modified layer, the modified layer having the fcc structure is formed in a thin layer shape with high density, and thus is difficult to be a starting point of fracture. When the average thickness of the modified layer is less than 1nm, the effect of improving the adhesion of the hard coating to the substrate cannot be obtained, and when the average thickness exceeds 10nm, the adhesion is adversely deteriorated. The average thickness of the modified layer is more preferably 2 to 9nm.

(C) Hard coating

(1) Composition of the composition

(a) Substrate-side single layer portion and surface-side single layer portion

The substrate-side single layer portion and the surface-side single layer portion of the present embodiment are each composed of a hard coating of a nitride body, wherein Al is the largest in proportion to metal (semi-metal-containing) elements, and the total content ratio (atomic ratio) of Al and Cr is 0.9 or more and at least B is contained in the hard coating of a nitride body. The abrasion resistance of the coating film is improved by the total content ratio (atomic ratio) of Al and Cr being 0.9 or more. In order to improve the abrasion resistance of the coating, the total content ratio (atomic ratio) of Al and Cr is preferably 0.90 to 0.99, the content ratio (atomic ratio) of Al is preferably 0.5 or more, and the content ratio (atomic ratio) of B is preferably 0.01 or more. If the total content ratio (atomic ratio) of Al and Cr, the content ratio (atomic ratio) of Al, and the content ratio (atomic ratio) of B are not within the specific ranges, the wear resistance is lowered. The term "nitride body" means that the total 1 of the N content ratio (atomic ratio) to the nonmetallic element content ratio (atomic ratio) is 0.5 or more, and the N content ratio (atomic ratio) is preferably 0.6 or more.

In the case where the substrate-side single layer portion and the surface-side single layer portion are a (AlCrB) N film, an (AlCrB) NO film, or an (AlCrB) NCO film, the composition of the film is preferably, in addition to unavoidable impurities, represented by the following general formula: (Al) _x Cr _1-x- _y B _y )N _1-e-f C _e O _f (wherein x, 1-x-y, 1-e-f, e and f represent the atomic ratios of Al, cr, B, N, C and O, respectively, and the numbers of x, y, e and f satisfy 0.5.ltoreq.x.ltoreq.0.75, 0.01.ltoreq.y.ltoreq.0.1, 0.ltoreq.e.ltoreq.0.03, and 0.ltoreq.f.ltoreq.0.010). The contents of the metal (semi-metal element-containing) element, N and O can be analyzed in combination with EPMA and TEM-EDS (hereinafter also referred to as "EDS") described below. The content of C can be analyzed by EPMA described later.

The atomic ratio x of Al is preferably in the range of 0.5 to 0.75. When x is less than 0.5, the oxidation resistance of the film is impaired due to the excessively small Al content. On the other hand, when x exceeds 0.75, a soft hcp-structured crystal phase is formed in the coating film, and abrasion resistance is impaired. x is more preferably 0.50 to 0.74.

The atomic ratio of Cr is preferably in the range of 0.49 to 0.15. When 1-x-y is less than 0.15, the Al content is too high, so that a soft hcp-structured crystal phase is formed in the coating film, and abrasion resistance is impaired. On the other hand, if 1-x-y exceeds 0.49, the content of Al in the film becomes too small, and the oxidation resistance is impaired. 1-x-y is more preferably 0.49 to 0.18.

The atomic ratio y of B is preferably in the range of 0.01 to 0.1. When y is less than 0.01, the additive effect cannot be obtained, and the lubricity of the coating is impaired. On the other hand, when y exceeds 0.1, the film becomes brittle. y is more preferably 0.01 to 0.08.

The atomic ratio of N contained in the (AlCrB) N coating, the (AlCrB) NO coating and the (AlCrB) NCO coating of the present embodiment is preferably 1 to 0.96. If 1-e-f is not within the specific range, the abrasion resistance of the coating film tends to be lowered. 1-e-f is more preferably 0.998 to 0.96.

The atomic ratio f of O contained in the (AlCrB) N film, the (AlCrB) NO film, and the (AlCrB) NCO film of the present embodiment is preferably 0.010 or less. If f exceeds 0.010, the oxygen content becomes excessive, and the abrasion resistance of the coating film tends to be lowered. f is more preferably 0.002 to 0.010.

The atomic ratio e of C contained in the (AlCrB) NCO coating film of the present embodiment is preferably 0.03 or less. If e exceeds 0.03, the abrasion resistance of the coating film is lowered. In order to improve the abrasion resistance of the coating, e is more preferably 0.01 to 0.03. In the case of the (AlCrB) N coating and (AlCrB) NO coating, the presence of unavoidable impurity levels (e.g., about.0.001 to 0.009) having e less than 0.01 is allowed.

(b) Lamination part

The laminated portion of the present embodiment is formed by alternately laminating an a layer of a nitride body containing at least B and a B layer of a nitride body containing at least Cr and B, the Ti being the largest in proportion of metal (semi-metal-containing) elements, and the Al being the largest in proportion of metal (semi-metal-containing) elements. In the layer a, the content ratio (atomic ratio) of Ti is preferably 0.65 or more, and the content ratio (atomic ratio) of B is preferably 0.01 or more. In the layer B, the content ratio (atomic ratio) of Al is preferably 0.42 or more, the content ratio (atomic ratio) of Cr is preferably 0.1 or more, and the content ratio (atomic ratio) of B is preferably 0.01 or more. If the content ratio (atomic ratio) of each element in the a layer and the b layer is not within the specific range, the abrasion resistance of the coating film is liable to be lowered. The term "nitride body" means that the total 1 of the N content ratio (atomic ratio) to the nonmetallic element content ratio (atomic ratio) is 0.5 or more, and the N content ratio (atomic ratio) is preferably 0.6 or more.

The composition of the metallic (semi-metallic) element of layer a, preferably, apart from unavoidable impurities, consists of the general formula: (Ti) _1-p-q-r B _p Al _q Cr _r ) (wherein 1-p-q-r, p, q and r respectively represent the atomic ratios of Ti, B, al and Cr, and the numbers of p, q and r satisfy 0.01.ltoreq.p.ltoreq.0.05, 0.02)Q is equal to or less than 0.2, and r is equal to or less than 0.01 and equal to or less than 0.1).

The atomic ratio of Ti is preferably 0.96 to 0.65 in terms of 1-p-q-r. If 1-p-q-r is not within the specific range, the rake face abrasion resistance of the coating film is reduced. 1-p-q-r is more preferably 0.96 to 0.8.

The atomic ratio p of B is preferably 0.01 to 0.05. If p is not within the specific range, the rake face abrasion resistance of the coating film is reduced. p is more preferably 0.01 to 0.03.

The atomic ratio q of Al is preferably 0.02 to 0.2. If q is not within the specific range, the rake face abrasion resistance of the coating film is reduced. q is more preferably 0.02 to 0.12.

The atomic ratio r of Cr is preferably 0.01 to 0.1. If r is not within the specific range, the rake face abrasion resistance of the coating film is reduced. r is more preferably 0.01 to 0.05.

The composition of the metallic (semi-metallic) element of layer b, preferably, apart from unavoidable impurities, consists of the general formula: (Al) _1-s-t-u Cr _s B _t Ti _u ) (wherein 1-s-t-u, s, t and u represent the atomic ratios of Al, cr, B and Ti, respectively, and the numbers of s, t and u satisfy 0.1.ltoreq.s.ltoreq.0.4, 0.01.ltoreq.t.ltoreq.0.08, and 0.03.ltoreq.u.ltoreq.0.1).

The atomic ratio of Al is preferably 0.86 to 0.42 in terms of 1-s-t-u. If 1-s-t-u is not within the specific range, the flank wear resistance of the coating is reduced. 1-p-q-r is more preferably 0.84 to 0.44.

The atomic ratio s of Cr is preferably 0.1 to 0.4. If s is not within the specific range, the flank wear resistance of the coating is reduced. s is more preferably 0.12 to 0.40.

The atomic ratio t of B is preferably 0.01 to 0.08. If t is not within the specific range, the flank wear resistance of the coating is reduced. t is more preferably 0.01 to 0.07.

The atomic ratio u of Ti is preferably 0.03 to 0.1. If u is not within the specific range, the flank wear resistance of the coating is reduced. u is more preferably 0.03 to 0.09.

The layer a and the layer b are both hard coatings of nitride main bodies. As a result of EDS analysis of nonmetallic elements (N, C, O) in the layers a and b, it was confirmed by qualitative analysis that C was contained, but the measurement result of C content was unstable, and accurate quantitative analysis of C was not possible. However, it was found that the respective content ratios (atomic ratios) of N, C and O for the a layer and the b layer were mainly N. That is, in the layers a and b, the content ratio of N (atomic ratio) is 0.5 or more, and in a preferred example, the content ratio of N (atomic ratio) is 0.6 or more, relative to the total 1 of the content ratios (atomic ratios) of N, C and O. Therefore, in tables 5 and 6 described later, the composition of each of the a layer and the b layer is represented by the composition of only the metal (semi-metal-containing) element.

(c) Effect of adding B to hard coating

The B content in the substrate-side single layer portion, the a layer and the B layer in the laminated portion, and the surface-side single layer portion is set to the above specific range, whereby the lattice distortion of crystal grains of each film increases. By this action, in the hard coating to which B is added, the coating hardness, abrasion resistance, and tool life are all improved.

(d) Effect of addition of C to hard coating

In the substrate side single layer portion, the a layer and the B layer of the laminated portion, and the surface side single layer portion, the lattice distortion of crystal grains of each film is further increased by setting the C content in the specific range on the premise that the B content in the specific range is set. By this action, in the hard coating with C added, the coating hardness, abrasion resistance and tool life are all further improved.

(2) Film thickness

The thickness (t 1) of the single layer portion on the substrate side in this embodiment is larger than the thickness (t 2) of the entire laminated portion. Further, t1 is preferably 1.0 to 5. Mu.m. When t1 is less than 1.0. Mu.m, flank wear tends to progress, and when t1 exceeds 5. Mu.m, adhesion of the single layer portion on the substrate side is significantly reduced. t1 is more preferably 1.2 to 5.0. Mu.m.

The thickness (t 2) of the entire laminated portion is preferably 0.5 to 2.5. Mu.m. When t2 is less than 0.5 μm, the rake face abrasion tends to advance, and when t2 exceeds 2.5 μm, the adhesion force of the laminated portion decreases. t2 is more preferably 0.8 to 2.2. Mu.m.

The film thickness (t 3) of the surface-side single layer portion of the present embodiment is preferably 0.3 to 5 μm. When t3 is less than 0.3 μm, the effect of suppressing the flank wear cannot be obtained, and when t3 exceeds 5 μm, the adhesion between the surface side single layer portion 35 and the laminated portion 34 is significantly reduced. t3 is more preferably 0.5 to 4.5. Mu.m.

The film thickness ratio (t 1/t 2) of the substrate-side single layer portion to the entire laminated portion of the present embodiment is preferably 1.0 to 5. The film thickness ratio (t 3/t 2) of the surface-side single layer portion to the entire laminated portion of the present embodiment is preferably 0.3 to 4. The ratio (t1+t3)/t 2 of the total film thickness of the substrate-side single layer portion and the surface-side single layer portion to the film thickness of the entire laminated portion in the present embodiment is preferably 1.0 to 10. If the film thickness ratios t1/t2, t3/t2 and (t1+t3)/t 2 are not within the above specific ranges, it is difficult to achieve both excellent flank wear resistance and rake wear resistance. t1/t2 is more preferably 1.2 to 5. t3/t2 is more preferably 0.5 to 3. (t1+t3)/t 2 is more preferably 1.2 to 8.

The film thickness (ta) of the a layer and the film thickness (tb) of the b layer constituting the laminated portion of the present embodiment are each preferably 3 to 30nm, although not particularly limited. If ta and tb are not within the above specific ranges, it is difficult to achieve both excellent flank wear resistance and rake wear resistance. More preferably, ta and tb are each 4 to 28nm.

The film thickness ratio (t 3/t 1) of the surface-side single layer portion to the base-side single layer portion is preferably 0.1 to 1.5. If t3/t1 is not within the above specific range, it is difficult to achieve both excellent flank wear resistance and rake wear resistance. t3/t1 is more preferably 0.2 to 1.2.

The "film thickness" of the non-planar substrate-side single layer portion, the laminated portion, and the surface-side single layer portion means "arithmetic average thickness".

(3) Lamination cycle of lamination section

As shown in fig. 2, the lamination period T of the a layer and the b layer in the lamination portion of the present embodiment is a distance (thickness) in the film thickness direction from the lower end of any a layer 1 layer to the upper end of the b layer 1 layer immediately above the adjacent a layer. T is 5-100 nm. When T is less than 5nm or exceeds 100nm, the abrasion resistance of the coating is reduced. T is preferably 10 to 90nm, more preferably 20 to 80nm.

In the laminated portion, the boundary between the a layer and the b layer may be blurred due to interdiffusion between the a layer and the b layer. In this case, the lamination period T may be measured as a distance in the lamination direction between two a layers arranged with the b layer interposed therebetween among 3 layers (for example, a layer, b layer, and a layer sequentially laminated) adjacent to each other in the lamination section. The distance between the two a layers is the distance between the joining points in the thickness direction of each a layer.

(4) Crystal structure

The X-ray diffraction pattern of the portion of the hard coating constituted by the substrate-side single layer portion and the laminated portion of the present embodiment is constituted by a single structure of fcc. Further, the X-ray diffraction pattern of the portion of the hard coating constituted by the substrate-side single layer portion, the laminated portion, and the surface-side single layer portion of the present embodiment is preferably constituted by a single structure of fcc. That is, the portion of the hard coating film according to the present embodiment is a fcc crystal phase, which contributes to the improvement of performance and the prolongation of life of the coated cutting tool. In addition, if the range is not present in the X-ray diffraction pattern, a micro phase other than fcc may be present in the hard coating. Only the crystal structure of the laminated portion can be analyzed by electron diffraction (TEM) capable of detecting a minute phase. In the above electron diffraction, the stacked portion is preferably configured mainly by fcc, and more preferably is configured by a single fcc structure, from the viewpoint of higher performance and longer lifetime.

In the above-mentioned X-ray diffraction pattern, the ratio I (200)/I (111) of the X-ray diffraction peak I (200) of the (200) plane to the X-ray diffraction peak I (111) of the (111) plane is preferably 0.2 to 0.37. If the ratio I (200)/I (111) is not within the above-mentioned specific range, it is difficult to suppress flank wear and rake wear in good balance. The ratio I (200)/I (111) is more preferably 0.25 to 0.36.

In the above-mentioned X-ray diffraction pattern, the ratio I (311)/I (111) of the X-ray diffraction peak I (311) of the (311) plane to the X-ray diffraction peak I (111) of the (111) plane is preferably 0.03 to 0.15. If the ratio I (311)/I (111) is not within the above-mentioned specific range, it is difficult to suppress flank wear and rake wear in good balance. The ratio I (311)/I (111) is more preferably 0.06 to 0.12.

(D) Mechanism for

The present inventors have intensively studied a high-performance and long-life nanolaminate film, and as a result, have found that (i) a substrate-side single layer portion having the above-mentioned specific composition is formed on a substrate, (ii) a layer a and a layer b having the above-mentioned specific composition are alternately laminated on the substrate-side single layer portion, and the lamination period T in the film thickness direction of the two layers is set to 5 to 100nm, and (iii) an X-ray diffraction pattern of a portion constituted by the substrate-side single layer portion and the lamination portion is constituted by a single structure of fcc, whereby flank wear and rake wear can be suppressed in a balanced and excellent manner as compared with the conventional one. That is, although not fully elucidated, it is known that the single layer portion on the substrate side and the b layer mainly suppress flank wear, and the a layer mainly suppresses rake wear (crater wear). Further, it is found that the effect of suppressing flank wear is further improved when the surface-side single-layer portion is formed.

In addition, as described above, when the ratio I (200)/I (111) is 0.2 to 0.37, flank wear and rake wear can be suppressed in a well-balanced manner. In the polycrystalline grains of each film constituting the substrate-side single layer portion and the laminated portion, and further the surface-side single layer portion, the increase in the (200) plane orientation and the increase in the (111) plane orientation are relatively suppressed, and thus the coated cutting tool of the present embodiment is considered to have high performance and long life.

In addition, it was found that the flank wear and the rake wear can be further suppressed in a well-balanced manner when the ratio I (200)/I (111) is in the range of 00.2 to 0.37 and the ratio I (300)/I (111) is in the range of 0.03 to 0.15. In the polycrystalline grains of each film constituting the substrate-side single layer portion and the laminated portion, and further the surface-side single layer portion, the increase in the (311) plane orientation and the increase in the (111) plane orientation are relatively suppressed, and thus the coated cutting tool of the present embodiment is considered to have high performance and long life.

[2] Film forming apparatus

An arc ion plating (hereinafter also referred to as "AI") device can be used in forming the hard coating film of the present embodiment. As shown in fig. 1, the AI device includes: a pressure reducing container 25; arc discharge

type evaporation sources

13, 27 mounted on a decompression container 25 via an insulator 14;

targets

10, 18 mounted on the arc discharge

type evaporation sources

13, 27; arc

discharge power sources

11, 12 connected to the arc

discharge evaporation sources

13, 27; a rotatable column 6 penetrating into the pressure reduction container 25 via the bearing portion 24; a chuck 8 supported on the support column 6 for holding the base material 7; a driving unit 1 for rotating the column 6; and a bias power supply 3 for applying a bias voltage to the substrate 7. The pressure reducing container 25 is provided with a gas introduction portion 2 and an exhaust port 17. The

arc ignition mechanisms

16, 16 are mounted on the pressure reducing container 25 via arc ignition

mechanism bearing portions

15, 15. The filament-type electrode 20 is attached to the pressure reducing container 25 via

insulators

19 and 19 in order to ionize the gas (argon gas, nitrogen gas, etc.) introduced into the pressure reducing container 25. A shield plate 23 is provided between the target 10 and the substrate 7 in the pressure reduction container 25 via a shield plate bearing portion 21. The shield plate 23 is moved in the vertical direction or the horizontal direction by the shield plate driving unit 22, for example, and the hard coating film of the present embodiment is formed after the shield plate 23 is not present between the target 10 and the substrate 7.

(A) Target for forming substrate-side single layer portion and surface-side single layer portion

(1) Composition of AlCrB alloy and AlCrBC alloy

AlCrB alloy or AlCrBC alloy used as a target for forming the substrate side single layer portion, the b layer and the surface side single layer portion (hereinafter also referred to as "substrate side single layer portion or the like") of the present embodiment is obtained by, for example, using Al powder or AlC powder and CrB alloy powder having predetermined compositions, blending and mixing the compositions of AlCrB alloy or AlCrBC alloy described below, molding the obtained mixed powder, and sintering the obtained molded product. The oxygen content of the AlCrB sintered alloy or AlCrBC sintered alloy produced by the above-described steps can be obtained by, for example, subjecting the alloy to a non-oxidizing atmosphere (for example, an argon atmosphere or a vacuum degree of 1X 10 ^-3 Pa～10×10 ^-3 Pa), the particle size of the Al powder or the AlC powder and the CrB alloy powder, and the range from the blending step to the sintering step are appropriately adjusted.

Preferably, the AlCrB alloy or AlCrBC alloy has the general formula: al (Al) _α Cr _1-α-β-γ B _β C _γ (wherein, alpha, 1-alpha-beta-gamma, beta and gamma respectively represent Al, cr, B and CThe numerical values of alpha, beta and gamma satisfy the composition expressed by that alpha is more than or equal to 0.4 and less than or equal to 0.8, beta is more than or equal to 0.04 and less than or equal to 0.165, and gamma is more than or equal to 0 and less than or equal to 0.035). By setting α, β, and γ to the above specific ranges, a single layer portion on the substrate side and the like of the present embodiment can be formed.

The atomic ratio α of Al is preferably in the range of 0.4 to 0.8. When α is less than 0.4, the Al content of the substrate side single layer portion or the like is too small, and the oxidation resistance of the substrate side single layer portion or the like is impaired. On the other hand, when α exceeds 0.8, a soft hcp crystal phase is formed in the substrate side single layer portion or the like, and abrasion resistance is impaired. The range of α is more preferably 0.45 to 0.78.

The atomic ratio of Cr, 1-alpha-beta-gamma, is preferably in the range of 0.56 or less. When 1- α - β - γ exceeds 0.56, the Al content of the base material side single layer portion or the like becomes too small, and oxidation resistance is impaired. The range of 1- α - β - γ is more preferably 0.485 to 0.025.

The atomic ratio β of B is preferably in the range of 0.04 to 0.165. If β is less than 0.04, the effect of adding B cannot be obtained. On the other hand, when β exceeds 0.165, the single layer portion on the substrate side and the like cannot hold the single structure of fcc in the X-ray diffraction pattern. The range of β is more preferably 0.05 to 0.16.

The atomic ratio γ of C is preferably 0.035 or less. When γ exceeds 0.035, the life of the coated cutting tool becomes short. The range of γ is more preferably 0.015 to 0.035.

(2) Oxygen content of AlCrB alloy or AlCrBC alloy

The oxygen content of the AlCrB alloy or AlCrBC alloy is preferably 2000-4000. Mu.g/g. In the case where the oxygen content is less than 2000. Mu.g/g and exceeds 4000. Mu.g/g, the atomic ratio f of O of the substrate-side single layer portion or the like is less than 0.002 or exceeds 0.010. The oxygen content of the AlCrB alloy or AlCrBC alloy is more preferably 2050 to 3900. Mu.g/g, particularly 2100 to 3800. Mu.g/g.

(B) TiB alloy target

The TiB alloy target used to form the modified layer and a layer of the present embodiments preferably has the general formula: ti (Ti) _1-δ B _δ (wherein 1-delta and delta respectively represent the atomic ratio of Ti and B, and 0.1.ltoreq.delta.ltoreq.0.5.) is satisfied. When δ is less than 0.1, a decarburized layer is formed, and a modified layer of fcc structure cannot be obtained. When δ exceeds 0.5, a fcc structured modified layer cannot be obtained. Delta is more preferably 0.10 to 0.3.

(C) Arc discharge type evaporation source and power supply for arc discharge

As shown in fig. 1, each of the arc

discharge evaporation sources

13 and 27 has a target 10 made of a modified layer or a TiB alloy for forming an a layer, and a target 18 made of an AlCrB alloy or an AlCrBC alloy for forming a single layer portion on the substrate side. For example, a direct current or a pulse current is applied to the target 10 or the target 18 as an arc current. Although not shown, it is preferable to provide magnetic field generating means (a structure composed of an electromagnet and/or a permanent magnet and a yoke) in the arc

discharge evaporation sources

13 and 27, and to form a magnetic field distribution of several tens gauss (for example, 10 to 50G) in the vicinity of the base material 7.

The droplets generated during the formation of the hard coating according to the present embodiment are the starting points of the destruction of the hard coating. Therefore, it is preferable to apply a direct arc current of 150 to 250A to the target 18 made of AlCrB alloy or AlCrBC alloy and the target 10 made of TiB alloy to suppress excessive droplet generation.

(D) Bias power supply

As shown in fig. 1, a bias voltage is applied from a bias power supply 3 to a substrate 7.

[3] Film formation conditions

The conditions of ion bombardment and the conditions of forming a hard coating according to the present embodiment will be described in detail for each step, but are not particularly limited.

(A) Cleaning process of substrate

After the base material 7 is set on the mounting jig 8 of the AI apparatus shown in fig. 1, the inside of the pressure reduction container 25 is kept at 1 to 5×10 ^- ² Pa (e.g., 1.5X10) ^-2 Pa), and the base material 7 is heated to a temperature of 250 to 650 ℃ by a heater (not shown). Although shown as a cylinder in fig. 1, the substrate 7 may take various shapes such as a solid end mill or a blade. The substrate 7 is composed of WC-based cemented carbide, for example. After the substrate 7 is heated, argon gas is introduced into the reduced pressure container 25 to form an argon gas atmosphere of 0.5Pa to 10Pa (for example, 2 Pa). In this kind ofIn the state, a direct current bias voltage or a pulse bias voltage of-250 to-150V is applied to the base material 7 by the bias power supply 3, and the surface of the base material 7 is bombarded and cleaned by argon ions.

When the substrate temperature is less than 250 ℃, there is no etching effect of argon ions, and when it exceeds 650 ℃, it is difficult to set the substrate temperature to a predetermined condition in the film forming process. The substrate temperature was measured by a thermocouple embedded in the substrate (the same applies to the following steps). If the pressure of the argon gas in the reduced pressure vessel 25 is outside the range of 0.5Pa to 10Pa, the bombardment treatment by the argon ions becomes unstable. When the dc bias voltage or the pulse bias voltage is less than-250V, arcing is caused to occur on the substrate, and when it exceeds-150V, the cleaning effect of the bombardment-based etching cannot be sufficiently obtained.

(B) Modified layer Forming Process

The formation of the modified layer of the substrate 7 is performed by ion bombardment of the substrate 7 of the target 10 using the TiB alloy. After cleaning the substrate 7, an argon atmosphere having a flow rate of 30sccm to 150sccm was formed in the reduced pressure container 25. An arc current (direct current) of 50 to 100A is applied from an arc discharge power source 11 to the surface of a TiB alloy target 10 mounted on an arc discharge evaporation source 13. The substrate 7 is heated to a temperature of 450 to 750 ℃, and a DC bias voltage of-1000V to-600V is applied from the bias power supply 3 to the substrate 7. The substrate 7 is irradiated with Ti ions and B ions by ion bombardment of the target 10 using the TiB alloy.

When the temperature of the substrate 7 is outside the range of 450 to 750 ℃, a modified layer having fcc structure is not formed, or a decarburized layer is formed on the surface of the substrate 7, and the adhesion to the single layer portion on the substrate side is significantly reduced. If the flow rate of argon gas in the reduced pressure container 25 is less than 30sccm, the energy of Ti ions or the like entering the substrate 7 is too strong, and a decarburized layer is formed on the surface of the substrate 7, thereby impairing the adhesion between the substrate and the single layer portion on the substrate side. On the other hand, if the flow rate of argon exceeds 150sccm, the energy of Ti ions or the like is reduced, and no modified layer is formed.

When the arc current is less than 50A, the arc discharge becomes unstable, and when it exceeds 100A, a plurality of droplets are formed on the surface of the substrate 7, and adhesion between the substrate and the substrate-side single layer portion is impaired. When the dc bias voltage is less than-100V, the energy of Ti ions or the like is too high, and a decarburized layer is formed on the surface of the base material 7, and when the dc bias voltage exceeds 600V, no modified layer is formed on the surface of the base material.

(C) Film formation step of hard coating film

(1) Film formation of substrate-side monolayer portion

The substrate-side single layer portion of the present embodiment is formed on the substrate 7 or on the modified layer in the case of forming the modified layer. At this time, an arc current is applied from the arc discharge power source 12 to the surface of the target 18 made of AlCrB alloy or AlCrBC alloy mounted on the arc discharge evaporation source 27 using nitrogen gas. At the same time, a direct-current bias voltage or a unipolar pulse bias voltage is applied from the bias power supply 3 to the substrate 7 controlled to a temperature described below.

(a) Substrate temperature

The substrate temperature at the time of film formation of the substrate-side single layer portion of the present embodiment is set to 400 to 550 ℃. When the substrate temperature is less than 400 ℃, the substrate side single layer portion is not sufficiently crystallized, and thus the substrate side single layer portion does not have sufficient lubricity and abrasion resistance. In addition, the residual stress increases, which causes peeling of the coating film. On the other hand, when the substrate temperature exceeds 550 ℃, the refinement of crystal grains of the single layer portion on the substrate side is excessively promoted, and the lubricity and abrasion resistance are impaired. The substrate temperature is preferably 480 to 540 ℃.

(b) Pressure of nitrogen

Nitrogen gas was used as the film forming gas for the substrate-side single layer portion of the present embodiment. The pressure (total pressure) of the nitrogen gas is set to 2.7Pa to 3.3Pa. If the pressure of the nitrogen gas is less than 2.7Pa, the nitriding of the single layer portion on the substrate side becomes insufficient, and the presence of non-nitrided hetero-phase results in not only shortening the life of the coated cutting tool but also increasing the oxygen content of the single layer portion on the substrate side. On the other hand, when the pressure of the nitrogen gas exceeds 3.3Pa, the oxygen content of the substrate-side single layer portion becomes too low, resulting in softening. The pressure of the nitrogen gas is preferably 2.8Pa to 3.2Pa, and more preferably 2.9Pa to 3.1Pa.

(c) Flow rate of nitrogen

The flow rate of nitrogen is preferably 750sccm to 900sccm. When the flow rate of nitrogen gas is less than 750sccm and exceeds 900sccm, it is difficult to adjust the pressure (full pressure) of the nitrogen gas to 2.7 to 3.3Pa. The flow rate of nitrogen is more preferably 770sccm to 880sccm.

(d) Bias voltage applied to substrate

In order to form the substrate-side single layer portion of the present embodiment, a bias voltage of direct current or unipolar pulse is preferably applied to the substrate. The bias voltage is preferably set to-160 to-100V. When the bias voltage is less than-160V, the B content is obviously reduced. On the other hand, when the bias voltage exceeds-100V, the life of the coated cutting tool becomes short. The bias voltage is further preferably set to-150V to-110V.

In the case of a unipolar pulsed bias voltage, the bias voltage represents a negative peak excluding the steep portion of the rise from zero to the negative side. The frequency of the unipolar pulse bias voltage is preferably 20kHz to 50kHz, more preferably 30kHz to 40kHz.

(e) Arc current

In order to suppress droplets during film formation of the single layer portion on the substrate side, the arc current (direct current) applied to the target 18 is preferably 150A to 250A. When the arc current is less than 150A, arc discharge becomes unstable, and when it exceeds 250A, droplets significantly increase, and abrasion resistance of the single layer portion on the substrate side deteriorates. The arc current is more preferably 160A to 240A.

(2) Film formation in laminated part

The laminated portion of the present embodiment is formed on the substrate-side single layer portion. The laminated portion may be the outermost layer. Specifically, the laminated portion of the present embodiment in which a layer and b layer are alternately stacked is formed by applying arc current to the target 18 (AlCrB alloy or AlCrBC alloy) and the target 10 (TiB alloy) while continuing the formation of the substrate-side single layer portion. The film forming conditions specific to the laminated portion are only (i) and (ii) below, and the other conditions are the same as those of the substrate-side single layer portion.

(i) The bias voltage applied to the substrate is preferably set to-140 to-80V. By shifting the bias voltage applied to the substrate at the time of film formation of the laminated portion to the positive voltage side with respect to the bias voltage of the substrate side single layer portion (the shift is preferably 5 to 30V), al becomes larger in the composition of the b layer of the laminated portion than in the composition of the substrate side single layer portion and the surface side single layer portion. With this structure, a coated cutting tool having high performance and long life can be obtained. When the bias voltage is less than-140V, the B content is greatly reduced, and when the bias voltage exceeds-80V, the service life of the coated cutting tool is shortened. A further preferred range of bias voltages is-130V to-90V.

(ii) In forming the film in the lamination portion, it is practical to apply arc current to both the target 18 and the target 10.

(3) Film formation of surface side monolayer portion

The surface-side single layer portion of the present embodiment is formed on the laminated portion as needed. For example, it is preferable to adjust the film formation time so that the film thickness ratio t3/t1 of the surface-side single layer portion to the substrate-side single layer portion is set to 0.1 to 1.5. Otherwise, the film forming conditions of the substrate side single layer portion are the same as those described above.

(4) Upper layer of laminated part or surface side single layer part

The laminated portion or the surface-side single layer portion may be the outermost layer, but at least one known hard coating may be provided on the laminated portion or the surface-side single layer portion as required. Examples of known hard coatings include (TiAl) N, (TiAlCr) N, (TiAlNb) N, (TiAlW) N, (TiSi) N, (TiB) N, tiCN, al ₂ O ₃ 、Cr ₂ O ₃ A hard coating of at least one layer of (AlCr) N and (AlCrSi) N.

Examples

The present invention will be described in more detail with reference to the following examples, but the present invention is of course not limited thereto. In the following examples and comparative examples, unless otherwise specified, the compositions of the metal element and the semi-metal element of the target were measured based on the fluorescent X-ray method, and the oxygen content was measured based on the carrier gas method (carrier gas hot extraction method). In the examples, the insert was used as the base material of the hard coating, but the present invention is not limited to this, and the present invention is applicable to cutting tools (end mill, drill, etc.) other than inserts.

Example 1

(1) Cleaning of substrates

A finishing milling insert base material made of WC-based cemented carbide having a composition containing 8.0 mass% of Co and the remainder of which is composed of WC and unavoidable impurities (Mitsubishi Hitachi Tools Co., ltd. Manufactured ZDFG300-SC shown in fig. 13) and an insert base material for physical property measurement (Mitsubishi Hitachi Tools Co., ltd. Manufactured SNMN 120408) were set on a holder 8 of an AI apparatus shown in fig. 1, and heated to 550 ℃ with a heater (not shown) simultaneously with vacuum evacuation. Thereafter, argon gas was introduced at a flow rate of 500sccm (sccm is 1atm and cc/min at 25 ℃ C., the same applies hereinafter), the pressure in the reduced pressure vessel 25 was adjusted to 2.0Pa, and a DC bias voltage of-200V was applied to each of the substrates (hereinafter also referred to as "substrate 7") and the substrate 7 was cleaned by etching using bombardment with argon ions.

(2) Formation of modified layer Using TiB alloy target

The flow rate of argon was set to 70sccm while maintaining the substrate temperature at 550℃to obtain a composition consisting of Ti _0.85 B _0.15 The target 10 of the TiB alloy represented by (atomic ratio) is disposed on an arc discharge evaporation source 13 to which an arc discharge power source 11 is connected. A direct current voltage of-800V was applied to the substrate 7 by the bias power supply 3, and an arc current (direct current) of 75A was applied from the arc discharge power supply 11 to the surface of the target 10, so that a modified layer having an average thickness of 5nm was formed on the surface of the substrate 7. The measurement of the average thickness of the modified layer was performed by the method described in patent No. 5967329.

(3) Formation of substrate-side single layer portion

Will be made of Al _0.55 Cr _0.35 B _0.10 The target 18 composed of an AlCrB sintered alloy having a composition of a metal element and a half metal element (atomic ratio) and an oxygen content of 2300. Mu.g/g was disposed on the arc discharge evaporation source 27 to which the arc discharge power source 12 of FIG. 1 was connected. The temperature of the substrate 7 was set to 450 ℃, and the total pressure of nitrogen gas in the pressure reduction vessel 25 set to a nitrogen gas atmosphere was set to 3.0Pa, and the flow rate of nitrogen gas was adjusted to 800sccm.

A dc voltage of-140V was applied to the substrate 7 by the bias power supply 3, and a dc arc current of 200A was applied from the arc discharge power supply 12 to the target 18, and a single layer portion on the substrate 7 was formed as a substrate side, having (Al _0.60 Cr _0.38 B _0.02 )N _0.994 O _0.006 (atomic ratio) a base material side single layer portion having a film thickness (t 1) of 2.0 μm.

(4) Formation of laminated portion

In addition to the application of-120V DC voltage to the substrate 7 by the bias power supply 3, the film forming condition of the substrate side single layer portion is maintained, and the composition of the substrate is Ti from the arc discharge power supply 11 _0.85 B _0.15 A direct arc current of 200A was applied to the TiB alloy target 10 shown in (atomic ratio), and the a layer and the b layer of 50 layers were alternately deposited on the single layer portion on the substrate side, thereby forming a laminated portion having a film thickness (t 2) of 1.0 μm as a whole. Thus, a coated cutting tool (milling insert) of the present embodiment was produced.

(5) Observation of sectional structure of hard coating

Fig. 3 is a Scanning Electron Microscope (SEM) photograph (magnification: 20000 times) showing a cross-sectional structure of the above-mentioned coated cutting tool. In fig. 3, 31 is a WC-based cemented carbide substrate, 33 is a substrate-side single layer portion, and 34 is a laminated portion. Since fig. 3 is a low magnification, the a layer and the b layer constituting the modified layer 32 and the laminated portion 34 are not visible.

(6) Lamination cycle of each film thickness and lamination portion of hard coating

The film thicknesses at the left and right ends are measured in the substrate-side single layer portion 33 and the laminated portion 34 in fig. 3, respectively, and the measured values are arithmetically averaged to obtain the film thickness (t 1) of the substrate-side single layer portion 33 and the film thickness (t 2) of the whole laminated portion 34. Further, a sample for observation by a transmission electron microscope (TEM, JEOL ltd. Manufactured JEM-2000) was prepared from the laminated portion 34 of fig. 3, and a dark field image (magnification 1600000) of the laminated portion of the sample was photographed by the TEM is shown in fig. 10. The lamination period T is measured at the center position of the a layers and the b layers alternately laminated from the upper side to the lower side of the lamination portion in fig. 10, and the measured values are arithmetically averaged to obtain T. T is 20nm.

(7) Composition of hard coating

The composition of the single layer portion on the substrate side was analyzed by measuring the center position in the thickness direction of the single layer portion on the substrate side in the cross section of the above-mentioned coated cutting tool under the conditions of an acceleration voltage of 10kV, an irradiation current of 0.05A and a beam diameter of 0.5. Mu.m by means of an electron probe microanalyzer EPMA (JEOL Ltd. Manufactured by JXA-8500F). Further, quantitative analysis of N element and O element in the substrate-side single layer portion was performed by EDS analysis using an energy dispersive X-ray spectrometer (EDS, UTW type Si (Li) semiconductor detector manufactured by NORAN Co., ltd.) mounted on TEM (JEM-2100) at the center position in the thickness direction of the substrate-side single layer portion. The measurement conditions for EPMA and EDS analysis are the same in other examples.

(8) X-ray diffraction pattern of hard coating

In order to observe the crystal structure of the portion of the hard coating film composed of the base material side single layer portion and the laminated portion in the cross section of the coated cutting tool, an X-ray diffraction apparatus (empyren manufactured by Panalytical corporation) was used, and the surface of the hard coating film was irradiated with cukα1 line (wavelength λ:0.15405 nm) under the following conditions to obtain an X-ray diffraction pattern (fig. 6).

Tube voltage: 45kV

Tube current: 40mA

Incidence angle ω: fixed at 3 °

2θ：20°～90°

In fig. 6, the (111) plane, (200) plane, (220) plane and (311) plane are all X-ray diffraction peaks of fcc structure. Therefore, it is known that the portion of the hard coating has a single fcc structure. In fig. 6, the X-ray diffraction peak not marked with an index is an X-ray diffraction peak of the WC-based cemented carbide substrate.

(9) Composition and crystal structure of laminated part

EDS analysis was performed by a UTW type Si (Li) semiconductor detector attached to TEM (JEM-2100) at position 4 of the white portion and position 5 of the black portion in the dark field image of TEM of fig. 10, respectively. As a result, the metal (semi-metal-containing) composition at position 4 (layer a) of the white portion was (Ti _0.90 B _0.01 Al _0.08 Cr _0.01 ). In addition, the metal (semi-metal-containing) composition of the black portion at position 5 (b layer) is (Al _0.57 Cr _0.33 B _0.02 Ti _0.08 )。

In

positions

4 and 5 of fig. 10, the nanobeam diffraction was performed by TEM (JEM-2100) under an acceleration voltage of 200kV and a camera length of 50 cm. Fig. 11 shows a diffraction image obtained at position 4. Fig. 12 shows a diffraction image obtained at position 5. In both fig. 11 and 12, diffraction patterns of the (002), (111) and (11-1) planes of the fcc structure were observed. From the results, the electron diffraction pattern of the laminated portion of this example was also a single structure of fcc.

(10) Tool life determination

As shown in fig. 13 and 14, the above-described coated cutting tool (hereinafter also referred to as "insert 40A") is attached to the front end portion 48 of the tool body 46 of the indexable insert type rotary tool (Mitsubishi Hitachi Tools co., ltd. Manufacturing ABPF30S32L 150) 50 by a set screw 47. The edge diameter of the indexable insert type rotary tool 50 is 30mm. The cutting process was performed under the following turning conditions using the indexable insert type rotary tool 50, and the rake face 45a and the flank face 45b of the insert 40A sampled per unit time were observed with an optical microscope (magnification: 100 times), and the processing time when either the wear width or the chipping width of the rake face 45a or the flank face 45b was 0.2mm or more was determined as the tool life.

Cutting conditions

Table 1 shows the composition of the targets of the AlCrB alloy and TiB alloy used. Table 2 shows the film forming conditions of the substrate-side single layer portion. Table 3 shows DC bias voltages applied at the time of film formation in the laminated portion. Table 4 shows the composition of the substrate-side single layer portion. Table 5 shows the metal (semi-metal containing) composition of the a layer and table 6 shows the metal (semi-metal containing) composition of the b layer. Table 8 shows the respective film thicknesses T1 and T2 of the whole substrate-side single layer portion and the whole laminated portion, the film thickness ratio T1/T2 of the whole substrate-side single layer portion and the whole laminated portion, and the lamination period T of the laminated portion. Table 9 shows the X-ray diffraction results of the portions of the hard coating film composed of the substrate side single layer portion and the laminated portion, the electron diffraction results of the a layer and the b layer, and the tool life.

Example 2

By adjusting the film formation time of each of the substrate-side single layer portion and the laminated portion, the film thickness T1 was set to 1.0 μm, the film thickness T2 was set to 0.8 μm, the film thickness ratio T1/T2 was changed to 1.25, and the lamination period T was changed to 16nm. Except for the foregoing, a coated cutting tool (milling insert) of this example was produced in the same manner as in example 1, and the tool life and the like were measured.

Example 3

By adjusting the film formation time of the single layer portion on the substrate side, the film thickness t1 was set to 5.0 μm, and the film thickness ratio t1/t2 was changed to 5. Except for the foregoing, a coated cutting tool (milling insert) of this example was produced in the same manner as in example 1, and the tool life and the like were measured.

Example 4

A substrate-side single layer portion and a laminated portion were sequentially formed on a substrate on which a modified layer was formed in the same manner as in example 1, except that the film formation time of the substrate-side single layer portion was adjusted and the film thickness t1 was set to 1.2 μm. Next, a film having (Al _0.60 Cr _0.38 B _0.02 )N _0.994 O _0.006 (atomic ratio) and the film thickness (t 3) was set to 1.2 μm. Thus, a coated cutting tool (milling insert) of this example was produced in which the film thickness ratio t1/t2 was changed to 1.2, the film thickness ratio t3/t2 was changed to 1.2, the film thickness ratio (t1+t3)/t 2 was changed to 2.4, and the film thickness ratio t3/t1 was changed to 1, and the tool life and the like were measured.

Example 5

A substrate-side single layer portion having a film thickness t1 of 4.0 μm and a laminated portion having a film thickness t2 of 1.0 μm were sequentially formed on the substrate on which the modified layer was formed in the same manner as in example 1, except that the film formation time of the substrate-side single layer portion was adjusted. Next, a film having (Al _0.60 Cr _0.38 B _0.02 )N _0.994 O _0.006 (atomic ratio) the film thickness (t 3) was set to 3.0 μm as a hard coating film. Thus, the film thickness ratio was made the coated cutting tool (milling insert) of the present example, in which t1/t2 was changed to 4, the film thickness ratio t3/t2 was changed to 3, the film thickness ratio (t1+t3)/t 2 was changed to 7, and the film thickness ratio t3/t1 was changed to 0.75, was measured for tool life and the like.

Example 6

As in example 1, a substrate-side single layer portion and a laminated portion were sequentially formed on the substrate on which the modified layer was formed. Next, a film having (Al _0.60 Cr _0.38 B _0.02 )N _0.995 O _0.005 (atomic ratio) the film thickness (t 3) was set to 0.5 μm as a hard coating film. Thus, a coated cutting tool (milling insert) of this example was produced with the film thickness ratio t1/t2 set to 2, the film thickness ratio t3/t2 set to 0.5, the film thickness ratio (t1+t3)/t 2 set to 2.5, and the film thickness ratio t3/t1 changed to 0.25, and the tool life and the like were measured.

Fig. 4 is a Scanning Electron Microscope (SEM) photograph (magnification: 20000 times) showing a cross-sectional structure of the coated cutting tool of example 4. In fig. 4, 31 is a WC-based cemented carbide substrate, 33 is a substrate-side single layer portion, 34 is a laminated portion, and 35 is a surface-side single layer portion. Since fig. 4 is a low magnification, the a layer and the b layer constituting the modified layer 32 and the laminated portion 34 are not visible. Fig. 7 shows an X-ray diffraction pattern of a portion of the hard coating film of example 4 including a base material side single layer portion, a laminated portion, and a surface side single layer portion. As can be seen from fig. 7, the hard coating of example 4 has a single fcc structure.

Fig. 5 is a Scanning Electron Microscope (SEM) photograph (magnification: 20000 times) showing a cross-sectional structure of the coated cutting tool of example 6. In fig. 5, 31 is a WC-based cemented carbide substrate, 33 is a substrate-side single layer portion, 34 is a laminated portion, and 35 is a surface-side single layer portion. Since fig. 5 is a low magnification, the a layer and the b layer constituting the modified layer 32 and the laminated portion 34 are not visible. Fig. 8 shows an X-ray diffraction pattern of a portion of the hard coating film of example 6, which includes a base material side single layer portion, a laminated portion, and a surface side single layer portion. As can be seen from fig. 8, the hard coating of example 6 has a single fcc structure.

With respect to examples 2 to 6, table 1 shows the compositions of the AlCrB alloy target and TiB alloy target of each example. Table 2 shows the film formation conditions of the substrate-side single layer portions of each example. Table 3 shows bias voltages of the stacked portions of the respective examples. Table 4 shows the composition of the substrate-side single layer portion of each example. Table 5 shows the composition of the metal (semi-metal containing) element of the a layer of each example, and table 6 shows the composition of the metal (semi-metal containing) element of the b layer of each example. Table 7 shows the compositions of the surface side single layer portions of each of examples 4 to 6. With respect to examples 2 to 6, table 8 shows the respective film thicknesses T1, T2 and T3, the respective film thickness ratios T1/T2, T3/T2, (t1+t3)/T2, T3/T1, and the respective lamination periods T of the respective examples. Table 9 shows the results of X-ray diffraction of the portion constituted by the substrate-side single layer portion and the laminated portion, and the portion constituted by the substrate-side single layer portion, the laminated portion, and the surface-side single layer portion, the results of electron diffraction of the a layer and the b layer of each example, and the tool lives of each example.

Examples 7 to 13

A coated cutting tool (milling insert) of each example was produced in the same manner as in example 1, except that the AlCrB alloy target and TiB alloy target of each example shown in table 1 were used, the film forming conditions of the substrate side single layer portion of each example shown in table 2 were used, and the bias voltages of the laminated portions of each example shown in table 3 were used. In example 7, the Al (Cr) addition amount of the AlCrB alloy target was changed relative to example 1. In examples 8 and 9, the B addition amount of the AlCrB alloy target was greatly changed relative to example 1. In examples 10 and 13, the total pressure of nitrogen was changed with respect to example 1. In embodiment 11, the bias voltage is changed with respect to embodiment 9. In example 12, the oxygen content of the AlCrB alloy target was greatly increased relative to example 1. Table 1 shows the compositions of the AlCrB alloy target and TiB alloy target of each example. Table 2 shows the film formation conditions of the substrate-side single layer portions of each example. Table 3 shows bias voltages of the stacked portions of the respective examples. Table 4 shows the composition of the substrate-side single layer portion of each example. Table 5 shows the composition of the metal (semi-metal containing) element of the a layer of each example, and table 6 shows the composition of the metal (semi-metal containing) element of the b layer of each example. Table 8 shows the film thicknesses T1 and T2, the film thickness ratios T1/T2, and the lamination periods T in each example. Table 9 shows the results of X-ray diffraction at the portion constituted by the substrate-side single layer portion and the laminated portion, the results of electron diffraction at the a layer and the b layer of each example, and the tool lives of each example.

Comparative example 1

A coated cutting tool (milling insert) of this comparative example, in which only a single layer portion on the substrate side was formed on the same substrate as in example 1, was produced in the same manner as in example 1 except that the AlCrB alloy target shown in table 1 was used, the total pressure of the nitrogen atmosphere in the reduced pressure vessel 25 at the time of film formation was set to 2Pa, the flow rate of nitrogen was set to 700sccm, and the DC bias voltage was set to-120V, and the tool life and the like were measured. Fig. 9 shows an X-ray diffraction pattern of a single layer portion on the substrate side of the coated cutting tool of comparative example 1.

Comparative example 2

A coated cutting tool (milling insert) of this comparative example, in which only a single layer portion on the substrate side was formed on the same substrate as in example 1, was produced and the tool life and the like were measured, in the same manner as in example 1, except that the AlCrB alloy targets shown in table 1 were used, the total pressure of the nitrogen atmosphere in the reduced pressure vessel 25 at the time of film formation was set to 3.5Pa, the flow rate of nitrogen gas was set to 900sccm, and the DC bias voltage was set to-120V.

Comparative example 3

A coated cutting tool (milling insert) of this comparative example was produced in the same manner as in example 1 except that the AlCrB alloy target having an oxygen content (420 μg/g) excessively small as shown in table 1 was used and the DC bias voltage was set to-120V, and only a single layer portion on the substrate side was formed on the same substrate as in example 1, and the tool life and the like were measured.

Comparative example 4

A coated cutting tool (milling insert) of this comparative example was produced in the same manner as in example 1 except that the AlCrB alloy target having an excessive oxygen content (5390 μg/g) shown in table 1 was used and the DC bias voltage was set to-120V, and only a single layer portion on the substrate side was formed on the same substrate as in example 1, and the tool life and the like were measured.

Example 14

A coated cutting tool (milling insert) of this example was produced and the tool life and the like were measured in the same manner as in example 1, except that a modified layer using a TiB alloy target was not formed on a WC-based cemented carbide substrate.

Examples 15 to 17

A coated cutting tool (milling insert) of this example was produced and the tool life and the like were measured in the same manner as in example 1, except that the AlCrBC alloy targets of each example shown in table 1 were used.

Table 1 shows the compositions of targets made of AlCrB alloy or AlCrBC alloy and TiB alloy targets for each of examples 14 to 17 and comparative examples 1 to 4. Table 2 shows the film formation conditions of the substrate-side single layer portions of each example. Table 3 shows DC bias voltages applied at the time of film formation at the laminated portion in each example. Table 4 shows the composition of the substrate-side single layer portion of each example. Table 5 shows the composition of the metal (semi-metal containing) element of the a layer of each example, and table 6 shows the composition of the metal (semi-metal containing) element of the b layer of each example. Table 8 shows the film thicknesses T1 and T2, the film thickness ratios T1/T2, and the lamination periods T in each example. Table 9 shows the results of X-ray diffraction at the portions of the hard coating film of each example composed of the substrate side single layer portion and the laminated portion, the results of electron diffraction at the a layer and the b layer of each example, and the tool lives of each example.

Table 10 shows the respective ratios I (200)/I (111) and the respective ratios I (311)/I (111) read from the X-ray diffraction patterns (fig. 6 to 9) of the portions of the respective hard films of examples 1, 4, and 6 and comparative example 1, respectively.

TABLE 1

TABLE 2

Note that:

(1) Pressure of nitrogen atmosphere.

(2) The target composed of AlCrB alloy or AlCrBC alloy is applied.

(3) Applied to the substrate.

TABLE 3

Note that: (1) applying to a substrate.

TABLE 4

TABLE 5

TABLE 6

TABLE 7

TABLE 8

Note that:

(1) Film thickness of the substrate side single layer portion.

(2) The thickness of the entire laminated portion is set.

(3) Film thickness of the surface side single layer portion.

(4) Film thickness ratio of the substrate-side single layer portion to the entire laminated portion.

(5) Film thickness ratio of the surface side single layer portion to the entire laminated portion.

(6) The ratio of the total film thickness of the substrate-side single layer portion and the surface-side single layer portion to the total film thickness of the laminated portion. Wherein the surface side single layer portion is not to be evaluated when not formed.

(7) Film thickness ratio of the surface-side single layer portion to the base-side single layer portion.

(8) Lamination period (arithmetic average) in the film thickness direction of the a layer and the b layer of the lamination portion.

TABLE 9

Note that:

(1) And (c) a result of X-ray diffraction at a portion constituted by the substrate-side single layer portion and the laminated portion.

(2) And X-ray diffraction results of the portions constituted by the substrate-side single layer portion, the laminated portion, and the surface-side single layer portion.

(3) And only the single layer portion on the substrate side.

As shown in table 9, each indexable insert rotary tool of examples 1 to 17 has a longer life than each indexable insert rotary tool of comparative examples 1 to 4. In particular, the indexable insert rotary tools of examples 15 to 17, in which the (AlCrB) NCO coating films (table 4) containing C of 0.01 to 0.03 (atomic ratio) were formed as the base material side single layer portion, had a lifetime equal to or longer than that of the indexable insert rotary tool of example 1. The indexable insert rotary tool of example 14, in which no modification layer was formed on the surface of the WC-based cemented carbide substrate, had a shorter life than each of the indexable insert rotary tools of examples 1 to 13 and examples 15 to 17, but had a longer life than each of the indexable insert rotary tools of comparative examples 1 to 4.

Since the indexable insert rotary tools to which the milling inserts of comparative examples 1 to 4 were attached each lacked the laminated portion according to the present invention, good wear resistance was not exhibited, and it was determined that the life was short.

TABLE 10

Example No.	I(200)/I(111)	I(311)/I(111)
			Example 1	0.30	0.06
Example 4	0.35	0.09
			Example 6	0.36	0.11
Comparative example 1	0.39	0.18

As can be seen from Table 10, with respect to the ratio I (200)/I (111), example 1 was 0.30, example 4 was 0.35, and example 6 was 0.36. In contrast, the ratio I (200)/I (111) of comparative example 1 was large and was 0.39. Regarding the ratio I (311)/I (111), example 1 was 0.06, example 4 was 0.09, and example 6 was 0.11. In contrast, the ratio I (311)/I (111) of comparative example 1 was large and was 0.18.

In the above examples, the substrate side single layer portion, the b layer, and the surface side single layer portion were formed into substantially the same composition using the targets composed of the same AlCrB alloy or AlCrBC alloy, but are not particularly limited. For example, a target composed of a plurality of different AlCrB alloys or AlCrBC alloys may be used, and the composition of either the b layer of the substrate-side single layer portion or the laminated portion, and further the surface-side single layer portion, may be appropriately changed within the scope of the present invention.

Description of the reference numerals

1: drive unit

2: gas introduction part

3: bias power supply

6: lower clamp (pillar)

7: substrate material

8: upper clamping tool

10. 18: cathode material (target)

11. 12: power supply for arc discharge

13. 27: arc discharge type evaporation source

14: insulation for fixing arc discharge type evaporation source

15: bearing part of arc ignition mechanism

16: arc ignition mechanism

17: air outlet

19: insulator for fixing electrode

20: electrode

21: bearing part of shielding plate

22: driving part of shielding plate

23: shielding plate

24: bearing part

25: pressure reducing container

31: WC-based cemented carbide substrate

32: modified layer

33: substrate side single layer portion

34: lamination part

35: surface side single layer part

40A: milling blade (blade base material)

45a: rake face of blade

46: tool body

47: fixing screw for blade

48: front end of tool body

50: cladding cutting tool (indexable insert type rotary tool)

a: layer a

b: layer b

Claims

1. A coated cutting tool having a hard coating on a substrate, characterized in that,

the hard coating film comprises a substrate-side single layer portion and a laminated portion in this order from the substrate side,

the substrate-side single layer portion is composed of a hard coating of a nitride body, wherein the hard coating of the nitride body contains at most Al in terms of the proportion of metal elements, the total content ratio of Al and Cr, that is, the atomic ratio is 0.9 or more, and at least B,

the laminated part is formed by alternately laminating an a layer of a nitride main body and a B layer of the nitride main body, wherein the a layer of the nitride main body contains at least B and the Ti is the largest in proportion of metal elements; the layer B of the nitride body contains at least Cr and B, and contains at least Al in a metal element ratio,

the metal element comprises a semi-metal element,

the lamination period of the a layer and the b layer in the film thickness direction is 5-100 nm,

the X-ray diffraction pattern of the portion constituted by the base material side single layer portion and the laminated portion is constituted by a single structure of fcc.

2. The coated cutting tool according to claim 1, wherein,

the thickness t1 of the substrate-side single layer portion is 1.0 to 5 [ mu ] m, the thickness t2 of the entire laminated portion is 0.5 to 2.5 [ mu ] m, and the thickness ratio t1/t2 of the substrate-side single layer portion to the entire laminated portion is 1.0 to 5.

3. The coated cutting tool according to claim 1 or 2, wherein,

the laminated part has a surface side single layer part, the film thickness t3 of the surface side single layer part is 0.3-5 mu m,

the X-ray diffraction pattern of the portion constituted by the base material side single layer portion, the laminated portion, and the surface side single layer portion is constituted by a single structure of fcc,

the surface-side single layer portion is composed of a hard coating of a nitride body, wherein the hard coating of the nitride body contains at most Al in terms of the proportion of metal elements, the total content ratio of Al and Cr, that is, the atomic ratio is 0.9 or more, and at least B,

the metal element includes a semi-metal element.

4. The coated cutting tool according to claim 1 or 2, wherein,

the ratio I (200)/I (111) of the X-ray diffraction peak I (200) of the (200) plane to the X-ray diffraction peak I (111) of the (111) plane in the X-ray diffraction pattern is 0.2-0.37.

5. The coated cutting tool according to claim 1 or 2, wherein,

the ratio I (311)/I (111) of the X-ray diffraction peak I (311) of the (311) plane to the X-ray diffraction peak I (111) of the (111) plane in the X-ray diffraction pattern is 0.03-0.15.

6. A method for manufacturing a coated cutting tool according to claim 1, wherein the coated cutting tool is manufactured by arc ion plating,

the substrate-side single layer portion and the target for forming the b layer are composed of, in addition to unavoidable impurities, an AlCrB alloy or an AlCrBC alloy having a general formula represented by: al (Al) _α Cr _1-α-β-γ B _β C _γ The expressed composition, wherein alpha, 1-alpha-beta-gamma, beta and gamma respectively represent the atomic ratio of Al, cr, B and C, the numbers of alpha, beta and gamma satisfy that alpha is more than or equal to 0.4 and less than or equal to 0.8, beta is more than or equal to 0.04 and less than or equal to 0.165, and gamma is more than or equal to 0 and less than or equal to 0.035,

the target for forming the a layer is composed of a TiB alloy having the general formula: ti (Ti) _1-δ B _δ The expressed composition, wherein, 1-delta and delta respectively represent the atomic ratio of Ti and B, the number of delta satisfies 0.1-0.5,

in a nitrogen atmosphere having a total pressure of 2.7Pa to 3.3Pa, the substrate temperature is 400 ℃ to 550 ℃, the bias voltage applied to the substrate when forming the substrate-side single layer portion is-160V to-110V, and the bias voltage applied to the substrate when forming the laminated portion is-140V to-80V.

7. The method of manufacturing a coated cutting tool according to claim 6, wherein,

comprises a step of forming a surface-side single layer portion on the laminated portion,

the bias voltage applied to the substrate at the time of forming the surface side single layer portion is set to-160V to-100V.

8. The method of manufacturing a coated cutting tool according to claim 7, wherein,

as the target for forming the surface side single layer portion, the same AlCrB alloy or AlCrBC alloy as the base material side single layer portion is used.

9. The method for manufacturing a coated cutting tool according to any one of claims 6 to 8, wherein,

when the laminated portion is formed, arc current is simultaneously applied to the target for forming the a layer and the target for forming the b layer.